Breather tube



Jn, 5, 1954 H. G. sTARcK BREATHER TUBE Filed May 28. 1951 J4' 2f j?2222i Sii- L-"1 L- ilu a M g R11: galli1 i l -i iM-r1* 111| u, a www lPatented Jan. 1.9514

BREATHER VTUBE Halvar Gr.V Starck, Redondo Beach, Calif., assignor toNorthrop Aircraft, Inc., Hawthorne, Calif., a corporation of CaliforniaApplication May 28, 1951, Serial No. 228,639

2 Claims. (Cl. 244-135) The present invention relates to the Venting offluid storage tanks.

It is usually advisable to vent fluid storage tanks to enable air fromoutside the tank to enter a fluid storage tank as fluid is withdrawntherefrom, so that equal pressures outside and inside the tanks aremaintained.

A problem which has confronted the designers of aircraft has been thatof designing fuel storage tanks wherein vent openings will remain abovethe level of the fuel during all attitudes of the aircraft in flight.

With this in mind, the breather tube of the present invention has amongits main objects the advantage of maintaining tank vent openings abovethe level of the fuel in a tank at all times, irrespective of theposition of the tank with respect to the fuel stored therein.

Briefly, the breather tube of the present invention, in one preferredembodiment, comprises a flexible tube having one end thereof open toatmosphere, the other end thereof extending through the wall of the tankand having the tube opening positioned above the maximum fuel leveltherein. The tank vent opening is connected to a floatable member havingan axial air passage therethrough, by a ball and socket assembly whichis also provided with an axial air passageA therethrough; the airpassages of the oatable member and the ball and socket connection beingcontinuous with the tube passage. Air enters the tank, lor vapor isallowed to escape from the tank through the flexible tube, the inneropening of which is maintained above the level of the fuel by thefloatable member.

Inasmuch as the embodiment of the present invention chosen forillustration, herein relates to aircraft, .the principles involved willbe more easily understood by reference to the specification drawingswherein:

Figure 1 is a side elevational view of an airplane storage tank partlyin section to show the construction of the breather tube in the specificembodiment described above.

Figure 2 is an elevational view of a diving aircraft which is `cut awayto show the fuel tank in section, showing the position of the vent tubewith respect to the level of the fuel in the tank.

An aircraft fuel storage tank Il), as shown in Figure 1, is providedwith a flexible breather tube II which is passed through the wall at thebottom of the tank I0. The lower end of the tube II has its opening I2positioned in atmosphere. The diameter of the tube II is determined bythe size of the tank I 0 and the rate of fuel withdrawal therefrom. Thetube I-I should be flexible enough to freely move on a fixed base like abuoy cable, in the fuel as the tank I0 changes position with respect tothe level of the fluid during the flight of the aircraft. However,l thetube i I should be resilient enough so that looping, kinking, orcollapsing thereof is pre'v vented. The normalr position of thebreatherY tube II in a full tank during level night is as shown in Fig.1, wherein the tube II is perpendicular to the bottom of the tank Ill.As the tank ID is emptied, the tube moves toward one side of the tank,the oatable member I4 maintaining the vent opening at the top, andeventually comes to rest against the tank wall ID.

A base member I3, vulcanized and sealed in the Wall of the tank IU, canbe used to fasten the breather tube II in position as shown for examplein Fig. l.

A hollow float member I5, which can be molded from a relativelylightweight plastic material which is impervious to aromatic fuel suchas phenolic resin for example, is provided with openings I5a and i512 atthe top and bottom thereof respectively, and is connected at the end ofthe breather .tube I I which is positioned above the level of the fuelby means of a ball member I6. 'I'he lower opening I5b of the floatmember I 4 is provided with a socket II which fits around a portion ofthe periphery of the ball member I6 which is movable therein. The shankI9 of the ball member IS is closely fitted into the upper opening 26 ofthe breather tube II and tightly sealed therein.

An axial air passage 2i is bored through the ball member I6 and iscontinuous with tube passage 22.

When an aircraft 23 is in an attitude other than level Iiight, as shownin Figure 2, the fuel tank I@ accordingly assumes a position, withrespect to the level of the fluid stored therein, which would usuallycover vent openings placed in the tank wall at the top of the tank ashas been the practice in many instances.

With the breather tube II of the present invention, however, the float-i member remains on the surface of the fluid, at all times, regardlessof the attitude of the aircraft 23, the Vent opening Ia in the tank Illventing the tank I0 during normal flight attitudes 0f the aircraft 23.

While in order to comply with the statute, the invention has beendescribed in language more or less specic as to structural features, itis to be understood that the invention is not limited to the specificfeatures shown, but that the means 3 and construction herein disclosedcomprise the preferred form of putting the invention into effect, andthe invention is therefore claimed in any of its forms or modificationswithin the legitimate and valid scope of the appended claims.

What is claimed is:

l. A breather tube for venting an aircraft fuel tank from full to empty,comprising a ilexible tube, the opening at one end of said tube beingpositioned in atmosphere, the opening at the other end of said tubebeing positioned in said tank above the level of fluid stored therein,t0 provide a continuous unobstructed air passage between the interior ofsaid tank and atm phere, a noatable member connected to said tubeopening in said tank by a freely movable ball and socket assembly, saidoatable member and said ball and socket assembly each having a centralair` passage therethrough normally axial of said tube and continuoustherewith, said oatable member maintaining said opening in said tankabove said fluid level irrespective of the position of said tank withrespect to said fluid during Hight of said aircraft.

2,. A breather tube for venting an aircraft fuel tank from full toempty, comprising a flexible tube, the opening .at one end of said tubebeing positioned Yin atmosphere, said Ilexible tube pas ing through thebottom of said tank and normally extending straight upwardly therein,the opening at the other end of said tube being positioned insaid tankabove the level of uid stored therein to provide a continuousunobstructed air passage between the interior of said tank andatmosphere, a floatable member having an air passage therethrough, aball and socket assembly connecting said oatable member with said tubeend in said tank, said ball member having an air passage therethroughaxial of said tube air passage and said oatable member air passage andcontinuous therewith, said oatable member being movable on said ballmember in accordance with move- .ment of said fluid to retain said tubeopening above the level of said fluid, irrespective of the position ofsaid tank with respect to said fluid during flight of Said aircraft.

HALVAR G. STARCK.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 1,636,540 Wiggins 7., July 19,1927 1,744,640 Kniel Jim,V 21,1.9.30 1,871,055 Hasbrouck Aug. 9, 1932 1,982,441 Loweke Nov. 27, v19,3%2,063,084 Farnon et al, Dec. .8, 19,36 2,475,834 Harvey July 12, `1949

